Breakthrough discovery in fight against malaria

Published: Thursday, February 5, 2009, 15:55 [IST]

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Washington, Feb 5 (ANI): Scientists have identified specific mosquito genes associated with resistance to a common class of insecticide, which could pave the way for developing new target in fight against malaria.

Understanding the genetic and biological basis of resistance to insecticides currently in use will be critical for more effective prevention measures in the field.

In the study, researchers led by Dr. Charles Wondji of the Liverpool School of Tropical Medical has identified the genetic basis of resistance to common pyrethroid insecticides in the mosquito Anopheles funestus, one of the major malarial vectors in Africa.

They studied strains of An. funestus that are both susceptible and resistant to pyrethroids, and narrowed down the potential genetic culprits to members of a family of genes coding for enzymes known as cytochrome P450s.

The P450s are common to all classes of organisms, and are considered a first line of defense against toxins.

The researchers found two cytochrome P450 genes in An. funestus that are associated with pyrethroid resistance.

Dr. Hilary Ranson of the Liverpool School of Tropical Medicine, a co-author of the study, explained that what makes this finding remarkable is that this particular type of cytochrome P450s were also recently implicated in pyrethroid resistance in Anopheles gambiae, the other major malaria-carrying mosquito in Africa.

"If the enzymes responsible for resistance are very similar in both species, there is a much greater incentive to invest efforts in identifying specific enzyme inhibitors with the knowledge that they will likely be effective at overcoming resistance in both major malaria vectors," said Ranson.

Also Ranson pointed out that it is critical that these mosquito P450 genes do not have close relatives in the human genome, which means that the targets developed against these mosquitoes should have low risk for toxicity in humans.

This report of genetic markers that can be used to predict insecticide resistance in laboratory populations of An. funestus may be a landmark finding in malaria prevention when applied to the evaluation of wild mosquito populations.

"Routine use of these molecular markers for resistance will provide early warning of future control problems due to insecticide resistance and should greatly enhance our ability to mitigate the potentially devastating effects of resistance on malaria control," said Ranson.